Nowadays, two-dimensional barcodes are ubiquitously found on a large number of items, including consumer products, spare parts, devices, fashion and/or luxury goods, perfumes, alcoholic and non-alcoholic beverages, tobacco products (cigarettes, cigars, loose tobacco and the like), etc. Furthermore, barcodes can also be found on all sorts of documents as items, including tickets, papers, currency bills, certificates, passports, ID cards, etc. Usually, these barcodes are used on the item for allowing a verification of the authenticity of the corresponding item. Specifically, by reading and decoding the two-dimensional barcode one can obtain information on whether (or to what degree of certainty) the corresponding item is authentic, genuine or complies with legal regulations, such as proper payment of tax and/or applicable fees.
FIG. 1A shows a schematic view of a two-dimensional barcode 10 according to the GS1 (trademark) data matrix ECC200 standard (GS1 being an International association providing standards for two-dimensional barcodes). This standard considers the two-dimensional barcode being formed by two types of elements, namely a first type element 11 and a second type element 12. Elements 11, 12 can be in form of dots or squares and can be formed on an item (document, product, package, etc.) by any suitable means. Specifically, the first type elements 11 can be printed onto an item surface whereby the non-printed areas then remain to form the second type elements 12. In general, printing a two-dimensional barcode in the context of the present disclosure is meant to include any suitable means, such as inter printing, laser printing, etching, embossing, etc. Any of these suitable ways to print the two-dimensional barcode on an item can be considered as long as the first and second type elements 11, 12 are formed on the item in a sufficiently stable fashion and remain distinguishable for a sufficient period of time.
The data matrix two-dimensional barcode 10 is compiled of an orientation pattern 14, 15 and a payload data pattern 13. The former orientation pattern is, in turn, compiled of a so-called L-shaped clock line 14 and an L-shaped solid line 15. Whereas the solid line 15 is compiled of elements of one type only, e.g. of first type elements 11, the clock line 14 is compiled of elements of alternating type. It may be further provided that the corner element of the clock line 14 is of a specific type, e.g. as shown of the first type. The orientation pattern of barcode 10 may also be referred to as the so-called finder pattern which facilitates reliable detection and decoding of the barcode by image processing. Specifically, the clock line 14 provides some information on the dimensions of the barcode and helps defining the columns and rows of the ordered grid along which the payload data pattern 13 is defined. The two-dimensional barcode 10 of FIG. 1A is of a so-called asymmetric type, since the numbers of rows and columns differ so as to assume generally a rectangle-like shape.
FIG. 1B shows a further example of a data matrix two-dimensional barcode in the form of a symmetric, i.e. square-like, barcode 19. Although both the orientation pattern and the payload data pattern are the same as in the one of FIG. 1A, barcode 19 has the same number of rows as the number of columns. Therefore, two-dimensional barcode 19 assumes the shape of a square.
FIG. 1C shows another type of two-dimensional barcode in the form of a so-called QR-code 20. Likewise, two-dimensional barcode 20 is compiled of first and second type elements 11, 12 which are described in conjunction with FIG. 1A. Also, two-dimensional barcode 20 is compiled of an orientation pattern 24 and a payload data pattern 23. It is to be noted that the payload data 23 does not need to completely fill the area as defined by the orientation pattern 24. Specifically, payload data pattern 23 may only make use of a part of that area and other parts may be used for printing clear text messages and/or graphical elements. In the case of the QR-code 20, the orientation pattern 24 is compiled of three marks which are, in turn, compiled of a black square, e.g. composed of 3×3 first time elements 11, surrounded by a square of second type elements 12, another square composed of first time elements 11 and—at least toward the internal sides of the barcode 20—sections of second type elements 12.
The decoding of a barcode usually begins with taking a (digital) image of the barcode attached on a given item. Such an image is then obtained as digital image data defining respective pixel values for the pixels of the image. This digital image data is then subject to image processing by means of a processing unit (e.g. CPU, Computer, Server, Embedded System, ASIC, etc.). Such processing may be divided into various individual steps for eventually decoding the data that is encoded in the two-dimensional barcode.
Since two-dimensional barcodes are usually formed as some kind of binary pattern (in the sense of being composed of elements of two different, distinguishable types), the amount of information that can be kept (encoded) in the two-dimensional barcode depends on the number of columns and rows of the two-dimensional barcode, i.e. the so-called barcode dimensions. In other words, the more columns or the more rows there are, the more distinguishable elements can be arranged in the pattern, and, with this, more bits of information can be encoded.
At the same time, however, the overall size of the two-dimensional barcode is usually subject to restrictions regarding the item's size and shape, the design and surface features of the item, etc. Specifically, it is usually not possible to cover an arbitrary part of an item with a two-dimensional barcode. On the contrary, manufacturers or distributors may substantially limit the area on an item where a two-dimensional barcode can be attached and the will usually want the area covered by a barcode to be as small as possible. In addition to this, also the size of the individual elements is subject to restrictions, since they need to remain distinguishable and durable according to the corresponding specifications, and, therefore, will need to be of some kind of minimal size. As a consequence, these limitations may result in the acceptable two-dimensional barcodes to carry only a limited amount of information. That is, the number of different and distinguishable pattern combinations is limited for a given barcode dimension and/or size.
Considering consumer goods, such as beverage cans/bottles, cigarette packages, and the like, it is clear that the two-dimensional barcode is usually printed on a large number of individual items. At the same time, the purpose of the two-dimensional barcode of providing some means of determining authenticity of the item may require the ability to encode a large number of different information sets in the attached barcodes. For example, some kind of identifier (ID), possibly also comprising some kind of signature, encrypted code or the like, is encoded in the two-dimensional barcode for later allowing authentication of the individual items, including also the detection of counterfeits and copies. Especially the latter can be determined for example by detecting in the field two identical IDs on different items which, for the case that each individual item has a unique ID, may readily uncover forgery.
There is therefore a need to increase the number of different and distinguishable patterns that can be encoded as a two-dimensional barcode, while at the same time maintaining the size of the individual elements and the size (dimension) of the two-dimensional barcode as such. More specifically, there is a need to allow the identification of a larger number of individual items by means of attaching two-dimensional barcodes while the size of the two-dimensional barcode as such can be maintained in order to keep the interference with the design and surface properties of the items as low as possible, and which maintains the size and appearance of the individual elements so as to maintain the robustness, reliability, and quality of the barcode in the field, especially during later reading and/or decoding.